HFC-134a (CF3CH2F, 1,1,1,2-tetrafluoroethane) is currently the most widely used coolant. Even though its ozone destroying potential (ODP) is zero, its global warming potential (GWP) is high and can remain in the atmosphere for a long time. When used in large quantity, it can cause global warming. Therefore, European Union passed the F-gas regulations in 2006, banning uses of fluorinated gas with GWP greater than 150 as coolants in the air conditioners in new cars from Jan. 1, 2011, and banning use of fluorinated gas with GWP greater than 150 as coolants in all new automotive air conditioners from Jan. 1, 2017.
In the search for a substitute for HFC-134a, 1,3,3,3-tetrafluoropropene (HFO-1234ze) is recognized as a future substitute for HFC-134a as a new generation coolant, because its various properties, including ODP=0 and GWP<100. HFO-1234ze is also thought to be promising as a next generation foaming agent. In addition, it can be used as a cleaning agent, aerosol propellant, solvent composition, insulation material, and fire extinguishing and flame retarding agent, etc. Its applications are wide and promising.
1,1,1,3,3-Pentafluoropropane (HFC-245fa) is being developed as an ultimate substitute for the widely used foaming agent trichlorofluromethane (CFC-11) and its transition substitute product 1,1-dichloro-1-fluroethane (HCFC-141b). It is recognized as the most promising third generation foaming agent substitute. In addition, HCFC-245fa is used as a coolant, cleaning agent, aerosol agent, a starting material for other fluorinated compounds, heat conducting medium, tobacco swelling agent, and extraction agent, etc. Its application is broad and wide.
Currently, industrial methods for the preparation of HCFC-245fa mainly involve gas phase fluorination of 1,1,1,3,3-pentafluropropane. And, the preparation methods for HFO-1234ze mainly use 1-chloro-3,3,3-trifluoropropene (HCFC-1233 zd) and 1,1,1,3,3-pentachloropropane (HCC-240fa) as the starting materials. For example, Japanese patent No. JP10007604 discloses methods using Cr, Ti, Ni, Al, Mn, Co etc. metal oxides supported on carbon as catalysts to fluorinate HCFC-1233zd to produce HFO-1234ze. These methods have relatively high one-way conversion rate. U.S. Patent publication No. 2005/0020862 and Chinese Patent application No. CN1852880 disclose methods that under the catalysis of a fluorination catalyst, fluorinate the starting material 1-chloro-3,3,3-trifluoropropene (HCFC-1233zd) to produce 1-chloro-1,3,3,3-tetrafluoropropane and 1,1,1,3,3-pentafluoropropane. Then, in liquid phase under the action of a strong base to remove HF and produce HFO-1234ze. Chinese Patent No. CN1852880A, Japanese Patent Nos. JP10007605, JP 11140002, and U.S. Pat. Nos. S6,124,510, 5,986,151, etc. disclose a method that, under the action of a suitable catalyst, dehydrofluorinate 1,1,1,3,3-pentafluoropropane to produce HFO-1234ze. This method has a relatively high one-way conversion rate. Chinese Patent Publication No. CN200710090535.2 and CN200810000765.X reported a method that converts 1,1,1,3,3-pentachloropropane, under the action of a fluorination catalyst, to HFO-1234ze. This method first fluorinates 1,1,1,3,3-pentachloropropane to produce HCFC-1233zd and a small amount of HFC-245fa. Then, without purification, the mixture is placed into a second fluorination reaction to produce HFO-1234ze. The product is separated by a distillation column to produce HFO-1234ze. The unreacted HCFC-1233zd and HFC-245fa are circulated back into the second reactor.
In the industrial production, HFC-245fa is mainly prepared in liquid phase, and HFO-1234ze is mainly prepared in gas phase. Production of HFC-245fa in the liquid phase generates a large amount of waste liquid and the production often cannot be continuous. And, in the gas phase production of HFO-1234ze, HFC-245fa is a side product, which would need to be further dehydrofluorinated. The dehydrofluoroination reaction tends to inactivate the catalysts. The present invention provides methods for co-producing HFO-1234ze and HFC-245fa. These methods can overcome the deficiency in the art and product two useful products at the same time.